ROBSON— ON THE CEPHALOPODA 



439 



The hectocotylus. This was referred to by Hoyle as comparable to that of P. vulgaris. 

 It should however be pointed out that in the present example of P. gardineri the hecto- 

 cotylus differs from that of P. vulgaris in that the seminal groove is well covered over by 

 its external edge, though it is possible that the loose external edge may be contracted or 

 relaxed according to the state of preservation. 



The radula (Text-fig. 4). 



Fig. 4. Polypus gardineri: Radula. 

 Cam. 6 oc. X 6 obj. Reich. 



Fig. 5. Polypus horbidus : Radula and 

 Mandibles. Cam. 6oc. x 6 obj. Reich. 



4. Polypus horridus D'Orb. Tabl. method. Ann. Soi. Nat. vii. p. 54, 1826. 

 One example, $, from Amirante, 20^25 fathoms (1418). 

 $, „ 25—80 „ (1401). 



,, sex indeterminate, young, Amirante, 30 fathoms (1420). 



Distribution previously known: Zanzibar; South Africa; Red Sea; Ceylon; Male Atoll. 



Mandibles. The distal extremity of the anterior ramus of the lower mandible is 

 markedly turned back and expanded. The upper mandible is very erect and anteriorly 

 presents a remarkably straight front. 



Radula. The first laterals are elongate. The second laterals exhibit a very heavy 

 external inferior angle, while the third laterals are tolerably stout. (Text-fig. 5.) 



5. Polypus venustus Rang. Magasin de Zoologie, Ann. 5-8, 1835-8, fig. 93. 



One example, ?, from between Peros and Salomon, Chagos, 20 fathoms (1541). 



The author has been unable to find any modern work upon this species. There is a 

 brief reference to it in Tryon's Manual of Conchology, vol. i, where the distribution is 

 given as "Algiei-s: Island of Goree." Tryon places it among his indeterminable species 

 and considers it to be a young specimen. 



The specimen obtained from the above locality agrees with Rang's description (and 

 figure) pretty closely. In one or two respects it differs, e.g. the chromatophores are not 

 aggregated into a median dorsal clump but are found clustered towards the anterior end 

 of the mantle. Nor are the ventral chromatophores disposed in the sparse even rows 

 indicated by Rang's figure but are more irregularly distributed. Otherwise the description 

 given by Rang applies very adequately to this specimen. Particularly significant is the 

 agi'eement on the following characters : " un peu doree k la partie dorsale " and " les bras... 

 avec des series de petites taches dordes repondant aux ventouses." 



56—2 



